Thermomechanical, Differential Scanning Calorimetry, and Electron Microscopic Study of Al–Cu Mixtures after Plastic Deformation under High Pressure

Mixtures of Al–Cu powders of various compositions were subjected to plastic deformation at a pressure of 1–4 GPa in an anvil-type high-pressure apparatus and studied by the thermomechanical method, as well as by differential scanning calorimetry (DSC) and energy dispersive X-ray spectroscopy. When deformed samples were heated, a decrease in thickness was recorded, which reached 40%. This effect depended on the material of the anvils and the pressure at which the treatment was carried out. The DSC study showed that, upon heating, an exothermic process occurs in the samples in the range of 168–180°C and a high-temperature endothermic process of aluminum melting takes place. The concentration dependences of the enthalpy of the processes had an extreme form. An electron-microscopic study found that, as a result of pressure treatment in the samples, the ratio of components changes and a new phase is formed, the amount of which increases with increasing deformation pressure, which is a characteristic feature of a chemical process.